Usage scenarios & operational management

The development and use of geothermal energy in near-surface to medium-depth systems is a key driver of the heating transition in Germany, thanks to its low operational and economic risks and its high flexibility and scalability for individual buildings, residential areas, and commercial zones. Our experts at Fraunhofer IEG have many years of experience in feasibility studies, planning, implementation, testing, and connection of geothermal probes and probe fields, as well as innovative solutions for existing buildings such as GeoStar.

We offer you all services in the field of innovative, near-surface to medium-depth geothermal supply systems. In addition to classic development and utilization concepts, this also includes coaxial probes up to a depth of 1000 m and double U-probes up to several hundred meters. We support your projects with numerical analysis and multi-criteria analyses, and assist you with innovation consulting, training, and product development. In addition, we strive to actively develop and optimize our own and external technologies and processes (e.g., heat transfer fluids, geothermal probes, grouting materials).

The GeoStar concept developed by Fraunhofer IEG shows how existing residential and commercial buildings can also use their subsoil for climate-neutral heating and cooling. Using the inclined drilling technology of mobile drilling rigs, such as Fraunhofer IEG's Bo.Rex, boreholes arranged in a star pattern are drilled at an angle of approximately 10° to a depth of several hundred meters to reach geothermal probes. Since this technology allows a large volume of soil to be tapped and used even under buildings with minimal surface space requirements, the limited space between existing buildings is sufficient to tap geothermal energy for efficient and sustainable heating and cooling. Once the drilling work has been completed and the connection to the building or distribution network has been established, the geothermal system is almost invisible. Since cooling and heating technology can be combined and smart operation allows for maximum efficiency of use, GeoStar is a success factor for the heat transition in established inner-city residential and commercial areas.

Our experts in the energy reuse of disused mining infrastructure analyze and evaluate existing mining infrastructure and its potential for use in heating and cooling applications. To this end, they determine heating and cooling potential and evaluate underground production or storage concepts for the use and integration of mine water, as well as the potential for coupling heating and cooling networks. In addition to digitizing mine images, we create three-dimensional mine models, plan drilling paths, and design the piping for connecting mine buildings to above-ground technologies, such as solar thermal and heat pump systems. Together with our drilling engineers and our own drilling team, we can implement projects for the development and geothermal reuse of mining infrastructures along the entire value chain for you.

One of the biggest cost drivers and risk factors in the development and use of underground infrastructure is the investment costs of drilling and expanding storage facilities. The reuse of existing wells in former oil and natural gas fields, as well as storage facilities and infrastructure, offers the opportunity to offset large investments and also the feasibility and discovery risk associated with the development of geothermal energy or energy and material storage.

Our experts at Fraunhofer IEG can examine and evaluate the ecological and economic potential of the available resources in already installed wells. To this end, basic modeling and simulations of reuse are combined with field measurements of integrity and all necessary framework parameters. We also create models for utilization and implementation or connection to infrastructures and consumers, such as the expansion of geothermal probes for the base load requirements of district heating networks or large individual consumers such as hospitals, industrial plants, or swimming pools. We also advise you on how you can evaluate and take into account the conversion of old natural gas and oil wells, mining structures, and underground storage facilities at the municipal and industrial heat planning level.

Using data acquisition and sensory monitoring, our experts at Fraunhofer IEG can monitor the operation and production of your underground infrastructures and thus make long-term forecasts for their operation. To this end, targeted sensory measurements of underground and surface operations are carried out and evaluated during development and test production. The results allow you to optimize operational management (e.g., production and injection rates of geothermal plants), reduce operational risks, and conduct a more detailed economic analysis of the operating site and possible field development for the expansion of further plants.

Once underground plants for energy or material production or storage are ready for operation, it is essential to parameterize all relevant factors for long-term, economical, and ecological operation as well as for field development. To this end, our experts at Fraunhofer IEG use digital twins and AI-supported tools to develop a robust utilization strategy for production and operational management based on existing and future data from the subsurface and operations.

For the strategic and economic implementation of underground infrastructures, such as geothermal sources and storage facilities, in energy infrastructures, numerous projects are usually carried out in exploration and production fields to be developed under mining law. The extensive use of geothermal energy, the commissioning of several underground storage facilities, or the production of resources from underground therefore requires planning services to make optimum use of the available space.

Our experts at Fraunhofer IEG base their expertise in field development and the associated expansion strategy on many years of experience. To this end, economic considerations are combined with long-term forecasts of production or storage in order to calculate the optimal distribution of plant locations with maximum efficiency. Digital twins and production monitoring of future operations help to provide forecasts for field development.